Coated article and method of production thereof



- at one time.

solvents and Patented Apr. 10, 1945 UNITED STATES PATENT OFFlCE coA'rnn ARTICLE AND METHOD or rnonncrron 'rmmuor Waldorf S. Traylor,

\ Hercules Powder Newport, Del, assignor to pany, Wilmington, Del., a corporation of Delaware No Drawing. Application June 27, 1941,

Serial No. 400,120

a Claims. (01.11745) I ness of coating since there is a definite limit to the-thickness of coating which can be applied The operation is usually carried out by applying a first coating to the fabric and then drying the coating to remove the then repeating the operation sucas for example atwo roll plastic mill or a calender stack composed of three or more rolls. Since no solvents are present, the plastic composition does not impregnate the fabric to any observable extent. However, the heat and pressure which are applied to the plastic to make it cessively until the proper thickness of coating is obtained. In the production of artificial leather it is usually necessary to apply at least about seven separate coats to the fabric. It is apparent that considerable handling of thefalbric is therefore necessary and the operation is consequently quite costly.- The volatile solvents which are used introduce serious fire hazards and also require use of solvent recovery systems to make the operation economically feasible. A high proportion of plasticizer has always been necessary with the nitrocellulose to provide sufllcient flexibility of the coating. In fact, as-much plasticizer as the coating will" tolerate without spewing at slightly elevated temperatures is usually included in the formula. Such large amounts of plasticizer are-necessary in the lacquer dopes since the dopes penetrate the material being coated and tend to stiffen it more than desired. To avoid suchstifiening the first coats are generally plasticized more heavily than the subsequent coats, and 'such coats are quite tacky.

flow cause it to penetrate the fabric lonly sufllciently to anchor the coating and insumcient to cause immobilization of the individual threads or fibers. Consequently no stiffening ofthe fabric occurs.

With use of other film formers heretofore used for coating cloth. such as for example nitrocellulose, solvents have' been necessary due to the nonthermopiastic nature of the nitrocellulose. Use of a small enough amount ofsolventto prevent impregnation has not been possible and still insure fiowability. Ethyl cellulose, being truly thermoplastic in character, is ideally adapted to application without use of solvents and thus makes possible the improvements in textile fabric coating described in accordance with this invention.

While ethyl cellulose may be used alone in the .process of the invention,'it will usually be desirable to include 'a plasticizer for the ethyl cellulose to provide coated fabrics having the most satisfactory characteristics.

It is an object of this invention to provide an improved method of coating textile fabrics.

It is another object toprovide an improved method of coatin textile fabrics which requires only one coating operation.

It is a further object to method of coating textile fabrics which eliminates the use of volatile organic solvents.

provide an improved carried out by means of heated power rolls, such The ethyl cellulose which is utilized in the compositions of this invention is the type which has an ethoxyl content in the range from about 41 to about 51%, andpreferably from about 44% to about 49%. The viscosity characteristic may vary widely and will usually be above about 7 centipoises and preferably between about 70 and 300' centipoises, as measured on a 5% solution in a solvent consisting of 70% toluene and 30% denatured ethyl alcohol. I

As plasticizers the compositions utilized may include dibutyl phthalateptricresyl phosphate,

.methyl phthalyl ethyl glycollate, chlorinated di-' phenyls, refined mineral oil, raw orair blown castor oil, soya bean oil, acetyl triethyl citrate. long oil-modified alkyd resins containing over of combined oil or fatty acid, etc. The

amount of plasticizer will vary with the. particular plasticizer, withthe properties desiredin the final coating and with the viscosity of the ethyl cellulose employed. The amount of plasticizer will generally not exceed about 60% by weight of the composition. o

Small amounts of modifying agents may be included in thecompositlons if desired. A small amount of a wax, not to exceed about 3.5 per cent av'be included toimprove water-resisting properties. The amount of wax included will in no case be suflicient to interfere with adhesion of the coating. With Japan wax, for example, 3.5% is the maximum amount utilizable, while no more than 1 per cent of paraffin wax or 0.5 per cent of carnauba wax can be included without being seriously detrimental to adhesion. Fillers, pigments, or dyestuffs may be included if desired.

The plastic compositions utilized in the invention may be prepared by mixing the ingredients in lump or powder form and eolloiding on heated rolls, heated Banbury mill or other suitable device for compounding plastic substances without use of solvents. he temperature employed in compounding the plastic will be suiilcient to render the composition flowable and will usually be .from about 90 C. to about 150 C.

In applying the plastic composition to a textile fabric in accordance with the method of the invention .the details of the operation will vary with the particular coating device employed. In general, however, the molten plastic composition in homogeneous condition ,will be applied by means of rolls to the textile fabric using heat and pressure sufllcient to flow the composition onto the fabric. The adjustment of the opening between the rolls will control the thickness of coating applied to the fabric. The fabric emerges from the nip of the coating roll uniformly coated with an adherent and flexible coating of any desired thickness. For example, in a heated two roll mill the plastic compositionis worked on the rolls until thoroughly softened and distributed on one roll and in amount sufilcient 'to form a uniform bead in the nip; With proper adjustment of the rolls to provide the desired thickness of the plastic on the roll and with the temperature sufflciently high to render the bead fluid and shiny, the textile fabric is threaded through the nip. Emerging from the nip it will be coated uniformly with the plastic and may be cooled to set the coating. 1

- With use of a calender stack in place of the two roll mill the coating principle will be the same. It will be desirable to preheat the fabric to the coating temperature prior to coating with the plastic composition and this can be done readily in the multiple roll calender stacks. The temperature of application of the plastic will generally fall within-the range of about C. to about 150 C. The specific temperature employed with any specific composition will be determined by the nature of the composition in question.

The coated textile fabric obtained as 'a result of the coating operation of the invention will be characterized as having a flexible coating tightly adhering to the surface of the fabric with substantially'no impregnation thereof and will have a coating thickness varying from a minimum of about one mil to a maximum of about mils. It will be suitable for such purposes as artificial leather, window shade cloth, waterproof wrapp ngs,.substitute for oil cloth, etc.

The various embodiments of the invention are I illustrated by the following specific examples:

Example I I A mixture of '15 parts by weight of ethyl cellulose having an ethoxyl content of about 48 per cent and a viscosity of about 100 centipoises, '75 Parts Of pale blown castor oil and 19 parts of chlorinated diphenyl was compounded on a heated two roll mill until uniformly heated and distributed on one 'roll and a cloth then fed through the nip. A coated cloth having a unimils thickness resulted.

Example II Example III A mixture composed of '17 parts by weight of ethyl cellulose having an ethoxyl content of about 48 per cent and a viscosity of about 300 centipoises, 23'parts by weight of refined mineral 011, 0.06 part by weight of Sudan Yellow dye, and 0.25 part by weight of titanium dioxide was milled on a heated two-roll mill at a temperature of about 300 F. until the composition was uniformly heated and distributed on one roll. A cotton duck fabric preheated to 300 F. was then fed through the nip and was coated uniformly with a flexible and adherent coating of the composition of about 10 mils thickness.

It will be understood that the details and examples hereinbefore set forth are illustrative only, and that the invention as broadly described and claimed is in no sway limited thereby.

What I claim and desire to protect by Letters Patent is:

1. The method of coating a textile fabric to provide a tightly adherent, flexible coating on the surface with substantially no impregnation thereof, which comprises applying to a textile fabric a molten plastic composition consisting of ethyl cellulose, a plasticizer therefore and from 0 to about 3.5% by weight of a wax as the fllm-forming components under heat and pressure sufficient tocause it to flow, then allowing the fabric 0 to cool.

2. The method of coating a textile fabric to provide a tightly adherent, flexible coating on the surface with substantially no impregnation thereof, which comprises applying to a textile fabric a molten plastic composition consisting of ethyl cellulose, a plasticizer therefor and from 0 to about 3.5% by weight of a wax as the flimforming components at a temperature of about 90 to about C. under pressure, then allowing the fabric to cool.

3. The method of coating a textile fabric to provide a tightly adherent flexible coating on the surface with substantially no impregnation thereof, which comprises applying to a textile fabric a molten plastic composition consisting of ethyl cellulose, a plasticizer therefor in an amount not in excess of about 60% by weight, and from O'to about 3.5% by weight of a wax as the film-forming components at a temperature of about 90 to about 150 C. under pressure, then allowing the fabric to cool.

4. A textile fabric carrying a tightly adherent. flexible surface coating applied thereto without substantial impregnation thereof, of a plastic composition consisting of ethyl cellulose, a plasticizer thereforand from 0 to about 3.5% by weight of 'a wax as the film-forming components.

said coating having a thickness from about one substantial impregnation thereof, of a plastic v t composition consisting of ethyl cellulose, a' plasticizer therefor in an amount not in excess of about 60% by weight, and from o to about 3.5%

by weight of a wax as the illm-toi'ming com- .ponents, said coating having a thickness from about one mil to about 100 nails.

6. A textile fabric carrying a tightly adherent. flexible surface coating applied thereto without substantial impregnation thereof, of a plastic composition consisting of ethyl cellulose and chlorinatedvdiphenyl, said coating having a thickness from about one mil to about 100 mile.

"z. A textile fabric carrying a tightly adherent.

flexible surface coating applied thereto without substantial impregnation thereof; of a plastic composition consisting of ethyl cellulose anc blown castor oil, said coating having a'thick ness from about one mil to about 100 mils.

t: .M S. TRAYLOR 

